configitems: register the test 'fakedirstatewritetime.fakenow' config

configitems: register the test 'fakedirstatewritetime.fakenow' config

--- a/tests/fakedirstatewritetime.py	Fri Oct 13 23:26:16 2017 +0200
+++ b/tests/fakedirstatewritetime.py	Sat Oct 14 00:15:37 2017 +0200
@@ -12,9 +12,17 @@
     dirstate,
     extensions,
     policy,
+    registrar,
     util,
 )
 
+configtable = {}
+configitem = registrar.configitem(configtable)
+
+configitem('fakedirstatewritetime', 'fakenow',
+    default=None,
+)
+
 parsers = policy.importmod(r'parsers')
 
 def pack_dirstate(fakenow, orig, dmap, copymap, pl, now):